System and method for sinus surgery

ABSTRACT

A method for treating a sinus cavity is provided. The method includes the steps of inserting a plasma applicator into a sinus cavity defined in a bone mass, positioning the plasma applicator adjacent a tissue formation, generating a selectively reactive plasma effluent at the plasma applicator and directing the selectively reactive plasma effluent at the tissue formation. The selective nature of the reactive plasma enables treatment of specific targets inside the sinus while minimizing the effect on other tissues. Such treatment includes, but not limited to, sterilization of bacterial colonies, vaporization of unwanted tissues or foreign masses, stimulation of tissues by enriching the content of reactive oxygen and nitrous oxide pathways, and combinations thereof.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a divisional application of U.S. patentapplication Ser. No. 14/159,758, filed on Jan. 21, 2014, now U.S. Pat.No. 9,532,826, which claims the benefit of and priority to U.S.Provisional Application Ser. No. 61/773,609, filed on Mar. 6, 2013, theentire contents of which are incorporated herein by reference.

BACKGROUND Technical Field

The present disclosure relates to plasma devices and processes forsurface processing and tissue removal. More particularly, the disclosurerelates to a system and method for generating and directing chemicallyreactive, plasma-generated species in a plasma device along withexcited-state species (e.g., energetic photons) that are specific to thesupplied feedstocks for treating tissue.

Background of Related Art

Electrical discharges in dense media, such as liquids and gases at ornear atmospheric pressure, can, under appropriate conditions, result inplasma formation. Plasmas have the unique ability to create largeamounts of chemical species, such as ions, radicals, electrons,excited-state (e.g., metastable) species, molecular fragments, photons,and the like. The plasma species may be generated in a variety ofinternal energy states or external kinetic energy distributions bytailoring plasma electron temperature and electron density. In addition,adjusting spatial, temporal and temperature properties of the plasmacreates specific changes to the material being irradiated by the plasmaspecies and associated photon fluxes. Plasmas are also capable ofgenerating photons including energetic ultraviolet photons that havesufficient energy to initiate photochemical and photocatalytic reactionpaths in biological and other materials that are irradiated by theplasma photons.

Chronic sinusitis originates from several sources including, but notlimited to, infection by bacteria that may form biofilms, fungus thatcan form large fungal masses within the sinus, allergic reactions toinfecting agents, chronic viral conditions such as HPV, and combinationsthereof. These sources create inflammation in the sinus cavity thatresult in eosinophils, which in turn concentrate in the sinuses creatingeven greater inflammation and the degeneration of the mucosa into polypformation and weakening of the underlying bone mass. Over time thesinuses cavities fill with foreign material or polyps that originatefrom the mucosa that lines the sinus cavity. Conventional treatmentsstrip the sinus cavity of all mucosa, which results in the sinus liningreforming from scar tissue rather than epithelial mucosa. Moreconservative conventional treatments focus on removing the bulk of thematerial while attempting to preserve as much mucosa as possible. Thepreferred surgical tool for sinus surgery is a microdebrider availablefrom many manufacturers and well known in the industry. These deviseshave no tissue selective properties and cut the softened bone equally aswell as the overlying tissue using mechanical cutting.

SUMMARY

Plasmas have broad applicability to provide alternative solutions toindustrial, scientific and medical needs, especially workpiece surfaceprocessing at low temperature. Plasmas may be delivered to a workpiece,thereby affecting multiple changes in the properties of materials uponwhich the plasmas impinge. Plasmas have the unique ability to createlarge fluxes of radiation (e.g., ultraviolet), ions, photons, electronsand other excited-state (e.g., metastable) species which are suitablefor performing material property changes with high spatial, materialselectivity, and temporal control. Plasmas may also remove a distinctupper layer of a workpiece but have little or no effect on a separateunderlayer of the workpiece or it may be used to selectively remove aparticular tissue from a mixed tissue region or selectively remove atissue with minimal effect to adjacent organs of different tissue type.

One suitable application of the unique chemical species is to drivenon-equilibrium or selective chemical reactions at or within theworkpiece to provide for selective removal of only certain types ofmaterials. Such selective processes are especially sought in biologicaltissue processing (e.g., mixed or multi-layered tissue), which allowsfor cutting and removal of tissue at low temperatures with differentialselectivity to underlayers and adjacent tissues. This is particularlyuseful for removal of biofilms, mixtures of fatty and muscle tissue,debridement of surface layers and removing of epoxy and othernon-organic materials during implantation procedures.

The plasma species are capable of modifying the chemical nature oftissue surfaces by breaking chemical bonds, substituting or replacingsurface-terminating species (e.g., surface functionalization) throughvolatilization, gasification or dissolution of surface materials (e.g.,etching). With proper techniques, material choices and conditions, onecan remove one type of tissue entirely without affecting a nearbydifferent type of tissue. Controlling plasma conditions and parameters(including S-parameters, V, I, Θ, and the like) allows for the selectionof a set of specific particles, which, in turn, allows for selection ofchemical pathways for material removal or modification as well asselectivity of removal of desired tissue type. The present disclosureprovides for a system and method for creating plasma under a broad rangeof conditions including tailored geometries, various plasma feedstockmedia, number and location of electrodes and electrical excitationparameters (e.g., voltage, current, phase, frequency, pulse condition,etc.).

The supply of electrical energy that ignites and sustains the plasmadischarge is delivered through substantially conductive electrodes thatare in contact with the ionizable media and other plasma feedstocks. Thepresent disclosure also provides for methods and apparatus that utilizespecific electrode structures that improve and enhance desirable aspectsof plasma operation such as higher electron temperature and highersecondary emission. In particular, the present disclosure provides forporous media for controlled release of chemical reactants.

Controlling plasma conditions and parameters allows for selection of aset of specific particles, which, in turn, allows for selection ofchemical pathways for material removal or modification as well asselectivity of removal of desired tissue type. The present disclosurealso provides for a system and method for generating plasmas thatoperate at or near atmospheric pressure. The plasmas include electronsthat drive reactions at material surfaces in concert with other plasmaspecies. Electrons delivered to the material surface can initiate avariety of processes including bond scission, which enablesvolatilization in subsequent reactions. The electron-driven reactionsact synergistically with associated fluxes to achieve removal rates ofmaterial greater than either of the reactions acting alone.

A method for treating a sinus cavity is provided by the presentdisclosure. The method includes the steps of inserting a plasmaapplicator into a sinus cavity defined in a bone mass, positioning theplasma applicator adjacent a tissue formation, generating a selectivelyreactive plasma effluent at the plasma applicator and directing theselectively reactive plasma effluent at the tissue formation. Theselective nature of the reactive plasma enables treatment of specifictargets inside the sinus while minimizing the effect on other tissues.Such treatment includes, but not limited to, sterilization of bacterialcolonies, vaporization of unwanted tissues or foreign masses,stimulation of tissues by enriching the content of reactive oxygen andnitrous oxide pathways, and combinations thereof.

A method for treating a tissue cavity is also contemplated by thepresent disclosure. The method includes the steps of inserting a plasmaapplicator into a tissue cavity and positioning a plasma applicatoradjacent the tissue formation. The plasma applicator includes a shafthaving a proximal portion and a deflectable distal portion and a lumendefined therein terminating in an opening at a distal end of the distalportion. The lumen is in fluid communication with an ionizable mediasource and one or more electrodes disposed at the distal portion andcoupled to a power source. The method also includes the steps ofgenerating a selectively reactive plasma effluent at the plasmaapplicator and directing the selectively reactive plasma effluent at thetissue formation.

The present disclosure also provides for a method for treating a sinuscavity. The method includes the steps of inserting a plasma applicatorinto a sinus cavity defined in a bone mass and positioning the plasmaapplicator adjacent a tissue formation. The method also includes thesteps of selecting one or more precursor feedstocks having higherchemical reactivity with the tissue formation than with the bone mass ofthe sinus cavity, supplying ionizable media and the precursor feedstocksto the plasma applicator and igniting the ionizable media and theprecursor feedstocks at the plasma applicator to form a selectivelyreactive plasma effluent. The method further includes the step ofdirecting the selectively reactive plasma effluent at the tissueformation.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of thedisclosure and, together with a general description of the disclosuregiven above, and the detailed description of the embodiments givenbelow, serve to explain the principles of the disclosure, wherein:

FIG. 1 is a schematic diagram of a plasma system according to thepresent disclosure;

FIG. 2 is a schematic view of a plasma device according to the presentdisclosure;

FIG. 3 is a cross-sectional view of the plasma device of FIG. 2 alonglines 3-3;

FIG. 4 is an internal perspective view of a surgical site; and

FIG. 5 is a flow chart of a method according to the present disclosure.

DETAILED DESCRIPTION

Plasmas are generated using electrical energy that is delivered aseither direct current (DC) electricity or alternating current (AC)electricity at frequencies from about 0.1 hertz (Hz) to about 100gigahertz (GHz), including radio frequency (“RF”, from about 0.1 MHz toabout 100 MHz) and microwave (“MW”, from about 0.1 GHz to about 100 GHz)bands, using appropriate generators, electrodes, and antennas. Choice ofexcitation frequency, the workpiece, as well as the electrical circuitthat is used to deliver electrical energy to the circuit affects manyproperties and requirements of the plasma. The performance of the plasmachemical generation, the delivery system and the design of theelectrical excitation circuitry are interrelated—as the choices ofoperating voltage, frequency and current levels (as well as phase)effect the electron temperature and electron density. Further, choicesof electrical excitation and plasma device hardware also determine how agiven plasma system responds dynamically to the introduction of newingredients to the host plasma gas or liquid media. The correspondingdynamic adjustment of the electrical drive, such as via dynamic matchnetworks or adjustments to voltage, current, or excitation frequency maybe used to maintain controlled power transfer from the electricalcircuit to the plasma.

Referring initially to FIG. 1, a plasma system 10 is disclosed. Thesystem 10 includes a plasma device 12 that is coupled to a power source14, an ionizable media source 16 and a precursor source 18. Power source14 includes any suitable components for delivering power or matchingimpedance to plasma device 12. More particularly, the power source 14may be any radio frequency generator or other suitable power sourcecapable of producing power to ignite the ionizable media to generateplasma. The plasma device 12 may be utilized as an electrosurgicalpencil for application of plasma to tissue and the power source 14 maybe an electrosurgical generator that is adapted to supply the device 12with electrical power at a frequency from about 0.1 MHz to about 2,450MHz and in another embodiment from about 1 MHz to about 13.56 MHz. Theplasma may also be ignited by using continuous or pulsed direct current(DC) electrical energy.

The precursor source 18 may be a bubbler or a nebulizer configured toaerosolize precursor feedstocks prior to introduction thereof into thedevice 12. The precursor source 18 may also be a micro droplet orinjector system capable of generating predetermined refined dropletvolume of the precursor feedstock from about 1 femtoliter to about 1nanoliter in volume. The precursor source 18 may also include amicrofluidic device, a piezoelectric pump, or an ultrasonic vaporizer.

The system 10 provides a flow of plasma through the device 12 to aworkpiece “W” (e.g., tissue). Plasma feedstocks, which include ionizablemedia and precursor feedstocks, are supplied by the ionizable mediasource 16 and the precursor source 18, respectively, to the plasmadevice 12. During operation, the precursor feedstock and the ionizablemedia are provided to the plasma device 12 where the plasma feedstocksare ignited to form plasma effluent containing ions, radicals, photonsfrom the specific excited species and metastables that carry internalenergy to drive desired chemical reactions in the workpiece “W” (e.g.,tissue) or at the surface thereof. The feedstocks may be mixed upstreamfrom the ignition point or midstream thereof (e.g., at the ignitionpoint) of the plasma effluent, as shown in FIG. 1 and described in moredetail below.

The ionizable media source 16 provides ionizable feedstock to the plasmadevice 12. The ionizable media source 16 is coupled to the plasma device12 and may include a storage tank, a pump, and a cooling source (notexplicitly shown). The ionizable media may be a liquid or a gas such asargon, helium, neon, krypton, xenon, radon, carbon dioxide, nitrogen,hydrogen, oxygen, etc. and their mixtures, and the like, or a liquid.These and other gases may be initially in a liquid form that is gasifiedduring application. The gases maybe cooled prior to ionization such asenergy is added the ionization process the effluent remains below thetargeted maximum temperature associated with cold plasma reactions.

The precursor source 18 provides precursor feedstock to the plasmadevice 12. The precursor feedstock may be either in solid, gaseous orliquid form and may be mixed with the ionizable media in any state, suchas solid, liquid (e.g., particulates or droplets), gas, and thecombination thereof. The precursor source 18 may include a heater, suchthat if the precursor feedstock is liquid, it may be heated into gaseousstate prior to mixing with the ionizable media.

In one embodiment, the precursors may be any chemical species capable offorming reactive species such as ions, electrons, excited-state (e.g.,metastable) species, molecular fragments (e.g., radicals) and the like,when ignited by electrical energy from the power source 14 or whenundergoing collisions with particles (electrons, photons, or otherenergy-bearing species of limited and selective chemical reactivity)formed from ionizable media 16. More specifically, the precursors mayinclude various reactive functional groups, such as acyl halide,alcohol, aldehyde, alkane, alkene, amide, amine, butyl, carboxlic,cyanate, isocyanate, ester, ether, ethyl, halide, haloalkane, hydroxyl,ketone, methyl, nitrate, nitro, nitrile, nitrite, nitroso, peroxide,hydroperoxide, oxygen, hydrogen, nitrogen, and combination thereof. Inembodiments, the chemical precursors may be water, halogenoalkanes, suchas dichloromethane, tricholoromethane, carbon tetrachloride,difluoromethane, trifluoromethane, carbon tetrafluoride, and the like;peroxides, such as hydrogen peroxide, acetone peroxide, benzoylperoxide, and the like; alcohols, such as methanol, ethanol,isopropanol, ethylene glycol, propylene glycol, alkalines such as NaOH,KOH, amines, alkyls, alkenes, and the like. Such chemical precursors maybe applied in substantially pure, mixed, or soluble form.

The precursors and their functional groups may be delivered to a surfaceto react with the surface species (e.g., molecules) of the workpiece“W.” In other words, the functional groups may be used to modify orreplace existing surface terminations of the workpiece “W.” Thefunctional groups react readily with the surface species due to theirhigh reactivity and the reactivity imparted thereto by the plasma. Inaddition, the functional groups are also reacted within the plasmavolume prior to delivering the plasma volume to the workpiece.

Some functional groups generated in the plasma can be reacted in situ tosynthesize materials that subsequently form a deposition upon thesurface. This deposition may be used for stimulating healing, killingbacteria, and increasing hydrophilic or hydroscopic properties. Inaddition, deposition of certain function groups may also allow forencapsulation of the surface to achieve predetermined gas/liquiddiffusion, e.g., allowing gas permeation but preventing liquid exchange,to bond or stimulate bonding of surfaces, or as a physically protectivelayer.

With reference to FIGS. 1 and 2, the precursor source 18 and theionizable media source 16 may be coupled to the plasma device 12 viatubing 114 and 113, respectively. The tubing 114 and 113 may be combinedinto unified tubing to deliver a mixture of the ionizable media and theprecursor feedstock to the device 12 at a proximal end thereof. Thisallows for the plasma feedstocks, e.g., the precursor feedstock and theionizable gas, to be delivered to the plasma device 12 simultaneouslyprior to ignition of the mixture therein.

In another embodiment, the ionizable media source 16 and the precursorssource 18 may be coupled to the plasma device 12 via the tubing 114 and113 at separate connections, such that the mixing of the feedstocksoccurs within the plasma device 12 upstream from the ignition point. Inother words, the plasma feedstocks are mixed proximally of the ignitionpoint, which may be any point between the respective sources 16 and 18and the plasma device 12, prior to ignition of the plasma feedstocks tocreate the desired mix of the plasma effluent species for each specificsurface treatment on the workpiece “W.”

In a further embodiment, the plasma feedstocks may be mixed midstream,e.g., at the ignition point or downstream of the plasma effluent,directly into the plasma. It is also envisioned that the ionizable mediamay be supplied to the device 12 proximally of the ignition point, whilethe precursor feedstocks are mixed therewith at the ignition point. In afurther illustrative embodiment, the ionizable media may be ignited inan unmixed state and the precursors may be mixed directly into theignited plasma. Prior to mixing, the plasma feedstocks may be ignitedindividually. The plasma feedstock is supplied at a predeterminedpressure to create a flow of the medium through the device 12, whichaids in the reaction of the plasma feedstocks and produces a plasmaeffluent. The plasma according to the present disclosure is generated ator near atmospheric pressure under normal atmospheric conditions.

The system 10 also includes a coolant system 15 for cooling the device12 and particularly the plasma plume 32. The coolant system 15 includesa supply pump 17 and a supply tank 18. The supply pump 17 may be aperistaltic pump or any other suitable type of pump known in the art.The supply tank 17 stores the coolant fluid (e.g., saline, propyleneglycol) and, in one embodiment, may maintain the fluid at apredetermined temperature. In another embodiment, the coolant fluid maybe a gas and/or a mixture of fluid and gas. The system 10 furtherincludes a negative pressure source 19 to siphon tissue and unreactedcomponents from the treatment site. The negative-pressure source 17 maybe a vacuum pump, fan, circulator, and the like and is coupled to thedevice 12.

With reference to FIGS. 2 and 3, the device 12 is shown as a plasmaapplicator 100. The applicator 100 includes a handle 101 and alongitudinal shaft 102 coupled thereto. The shaft 102 includes aproximal portion 104 coupled to the handle 101 and a distal portion 106.The catheter shaft 102 includes a plasma lumen 103 defined therein andextending the entire length thereof and terminating in an opening 105 atdistal end of the distal portion 106. The shaft 102 may have a diameterfrom about 5 mm to about 10 mm allowing the applicator 100 to beinserted through operating ports for application of the plasma effluent32 at the operating site during laparscopic procedures or throughnatural body orifices. In another embodiment, the applicator 100 may beconfigured for use within or accompanied by a flexible endoscope.

In one embodiment, the distal portion 106 is configured for controlleddeflection. A pull-wire 107 (FIG. 3) or another suitable actuationmechanism extends from the handle 101 at the proximal end of thecatheter 100 through a lumen in the catheter shaft 102 and is fastenedto the distal portion 106. The pull-wire 107 is movable from a firstgenerally relaxed position wherein the distal portion 106 is disposed ina generally longitudinally-aligned position relative to the proximalportion 104 to a second retracted or tensed position wherein the distalportion 106 flexes (e.g., deflects) from the proximal portion 104 at adesired angle as shown in FIG. 2.

The distal portion 106 is constructed to be more flexible than theproximal portion 104, such that when the handle 101 is pulled back orotherwise actuated, the pull-wire bends the distal portion 106 from anundeflected position to a deflected position. In particular, theproximal portion 104 may include a wire or other support materials (notshown) therein to provide tensile strength to the catheter shaft 102while still maintaining flexibility for maneuvering through a vascularsystem. The distal portion 106 is formed from a flexible biocompatiblematerial such as polytetrafluoroethylene, polyurethane, polyimide, andthe like to allow for maneuverability thereof.

The applicator 100 includes two or more electrodes 108 and 110 disposedat the distal portion 106. The electrodes 108 and 110 may be formed froma conductive material and have a ring-like shape. The electrodes 108 and110 may be disposed over the distal portion 106 to provide forcapacitive coupling with the ionizable media. In another embodiment, theelectrodes 108 and 110 may be formed as needle electrodes (e.g., pointedtip) and may be disposed within the distal portion 106.

The electrodes 108 and 110 are coupled to conductors (not shown) thatextend through the catheter shaft 102 and are connected to the powersource 14 via electrical connectors 112. The catheter shaft 102 is alsocoupled to the ionizable media source 16 via gas tubing 114 and to theprecursors source 16 via tubing 113. The ionizable media source 16 andthe precursors source 16 may include various flow sensors andcontrollers (e.g., valves, mass flow controllers, etc.) to control theflow of ionizable media to the applicator 100. In particular, the lumen103 is in gaseous and/or liquid communication with the ionizable mediasource 16 and the precursors source 18 allowing for the flow ofionizable media and precursor feedstocks to flow through the cathetershaft 102 to the distal portion 106. The ionizable media in conjunctionwith the precursor feedstocks is ignited by application of energythrough the electrodes 108 and 110 to form plasma plume 32 exitingthrough the opening 105.

The applicator 100 also includes a suction lumen 150 coupled to thenegative pressure source 19. This allows for the removal of unreactedfeedstocks, debris and tissue particles to be removed from the tissuesite. The lumen 150 may be incorporated into the shaft 102 (FIG. 3) ormay be a separate tube coupled in parallel to the shaft 102.

The applicator 100 is suitable for treatment of various sinus cavities,such as paranasal sinuses. Sinuses are commonly accessed through nasalpassages using open or endoscopic instruments. Treatment of sinuscavities may involve debulking of the soft tissue located within thesinuses to prevent infections thereof. In particular, the goal of theprocedure may be to remove polyps, tumors, fungal masses and othertissue structures while preserving as much of the mucosal lining aspossible.

With reference to FIGS. 4 and 5, a functional sinus procedure using theapplicator 100 is discussed. FIG. 4 illustrates the paranasal sinusesand FIG. 5 illustrates a flow chart of a method for treating thesinuses. The surgical site includes multiple sinus cavities 200 formedwithin the bone mass 202. The sinus cavity 200 includes a formation 204(e.g., tumors, polyps, fungal masses, etc.) that affects the health ofthe sinus cavities 200.

In step 300, the applicator 100 inserted into the sinus cavity 200through a nasal cavity 203. Access may be gained through or byenlargement of an existing ostium or creating an opening to the sinuscavity 200 from the nasal cavity 203 or perforation through other organs(e.g., percutaneous).

The distal portion 106 may be deflected to direct the plasma effluent 32toward the tissue formation 204. In one embodiment, the deflection maybe from about 0° to about 45° with respect to a longitudinal axisdefined by the shaft 102. In step 302, the ionizable media along withprecursors is supplied to the applicator 100 and is ignited therein toform the plasma effluent 32. In one embodiment, the ionizable media maybe argon, helium or a mixture thereof and the precursors may be hydrogenperoxide, water, oxygen, nitrogen or mixtures thereof.

In step 304, the applicator 100 is moved across the tissue formation 204ensuring that the plasma effluent 32 is directed at the tissue to removethe soft tissue. As tissue is ablated, unreacted tissue particles andother debris is removed from the treatment site through the suctionlumen 150 via the negative pressure source 19. The temperature of theplasma effluent 32 is from about 60°, allowing the plasma to be usedwithin the confines of the sinus cavity 200 without ablating surroundingcritical tissue masses. The relatively low temperature of the plasmaeffluent 32 does not affect its ability to remove tissue, since theprimary effect on tissue is due to the chemical reactivity of the plasmaconstituents (e.g., ionized plasma feedstocks).

The precursors supplied to the applicator 100 are specifically chosen togenerate a selectively reactive plasma effluent 32. In other words, theprecursors, when ignited, produce a plasma effluent 32 that interactswith certain types of tissue, namely tissue formation 204, and haslittle to no effect on the underlying bone tissue. The selectedprecursor feedstocks have higher chemical reactivity with the tissueformation 204 relative to the chemical reactivity with the calcifiedtissue (e.g., bone). This allows for the plasma effluent 32 to etch andremove the tissue formation 204 without perforating the bone.

The plasma effluent 32 ablates and coagulates tissue via heat to stopbleeding. The plasma effluent 32 effectively ablates tissue formation204 while simultaneously cauterizing the tissue preventing bleeding. Inone embodiment, bleeding may be also controlled by administration ofvarious drugs (e.g., hemostatic agents) that prevent bleeding within thesinus cavity 200. The drugs may be administered topically to the tissueor through the plasma effluent 32 as chemical precursor feedstocks.

Sinus cavities may be very close to the brain or orbit of the eye,making conventional instruments, such as microdebriders very dangerousdue to their aggressive cutting action that may remove the surroundingbone tissue and damage nearby organs. In addition, diseased sinuses havealready thinned bones further reducing differentiation between targetedsoft tissues and bone tissue, thereby further increasing the possibilityof perforation into adjacent critical structures.

The present disclosure prevents such damage without requiring great careand expensive surgical navigational systems (e.g., endoscopes) that arepractically required when using conventional microdebriders. The presentdisclosure provides for a chemically reactive plasma that has higherchemical reactivity with the soft tissue than calcified tissue (e.g.,bone) thereby etching the soft tissue while leaving calcified orpartially calcified tissue unaffected. This provides for safer removalof tissue masses near critical structures. The reactivity, removal ratesand/or selectivity of the plasma effluent may be modified by supplyingdifferent chemical precursors to the applicator 100 based on the tissuebeing treated.

The applicator 100 also provides another advantage over mechanicalmicrodebriders, namely, a deflectable distal portion 106. Mechanicaldebriders and/or cutters have inflexible shafts which are eitherstraight or curved having fixed radial bends in the instrument shaft.Deflection of the distal portion 106 allows for usage of the applicator100 at virtually any reach within a general target mass or within thesinuses.

The plasma effluent according to the present disclosure also generateslittle heat and may be produced at a relatively low temperature (e.g.,room temperature). This provides another advantage over conventionalmethods that utilize electrosurgical instruments. Such instrumentsgenerate too much heat that is poorly dissipated within the sinuses,which may damage critical structures.

Although the illustrative embodiments of the present disclosure havebeen described herein with reference to the accompanying drawings, it isto be understood that the disclosure is not limited to those preciseembodiments, and that various other changes and modifications may beeffected therein by one skilled in the art without departing from thescope or spirit of the disclosure. In particular, as discussed abovethis allows the tailoring of the relative populations of plasma speciesto meet needs for the specific process desired on the workpiece surfaceor in the volume of the reactive plasma, such adapting the disclosedsystem and method for use on other body cavities where selective removalof tissue is desired.

What is claimed is:
 1. A method for treating a tissue cavity, the methodcomprising: inserting a plasma applicator into a tissue cavity having atissue formation; positioning the plasma applicator adjacent the tissueformation, the plasma applicator including: a shaft having a proximalportion, a deflectable distal portion, and a lumen defined thereinterminating in an opening at a distal end of the distal portion, thelumen being in fluid communication with an ionizable media source; andan electrode disposed at the distal portion and coupled to a powersource; igniting ionizable media and a precursor feedstock at the plasmaapplicator to form a selectively reactive plasma effluent, the precursorfeedstock having a higher chemical reactivity with the tissue formationthan with a bone mass of the tissue cavity; and directing theselectively reactive plasma effluent at the tissue formation, whereinthe selectively reactive plasma effluent selectively removes the tissueformation without perforating bone.
 2. The method according to claim 1,wherein positioning the plasma applicator includes: deflecting thedistal portion of the plasma applicator to direct the distal portiontoward the tissue formation.
 3. The method according to claim 1, furthercomprising applying a hemostatic agent to the tissue formation.
 4. Themethod according to claim 1, wherein the precursor feedstock is selectedfrom the group consisting of hydrogen peroxide, water, oxygen, andnitrogen.
 5. The method according to claim 1, wherein the ionizablemedia is selected from the group consisting of argon and helium.
 6. Themethod according to claim 1, wherein igniting the ionizable media andthe precursor feedstock further includes supplying power to the plasmaapplicator.
 7. The method according to claim 1, further comprisingsupplying coolant to the plasma applicator.
 8. The method according toclaim 1, further comprising supplying suction to the distal end of theshaft.
 9. A method for treating a sinus cavity, the method comprising:inserting a plasma applicator into a sinus cavity defined in a bonemass; positioning the plasma applicator adjacent a tissue formation;selecting a precursor feedstock to have a higher chemical reactivitywith the tissue formation than with the bone mass of the sinus cavity;supplying ionizable media and the precursor feedstock to the plasmaapplicator; igniting the ionizable media and the precursor feedstock atthe plasma applicator to form a selectively reactive plasma effluent;and directing the selectively reactive plasma effluent at the tissueformation, wherein the selectively reactive plasma effluent selectivelyremoves the tissue formation without perforating bone.
 10. The methodaccording to claim 9, wherein positioning the plasma applicatorincludes: deflecting a distal portion of the plasma applicator to directthe distal portion toward the tissue formation.
 11. The method accordingto claim 9, further comprising supplying a hemostatic agent to thetissue formation.
 12. The method according to claim 11, wherein theprecursor feedstock includes the hemostatic agent.
 13. The methodaccording to claim 9, wherein the plasma effluent has a maximumtemperature of about 60° C.
 14. The method according to claim 9, whereinthe precursor feedstock is selected from the group consisting ofhydrogen peroxide, water, oxygen, and nitrogen.
 15. The method accordingto claim 9, wherein the ionizable media is selected from the groupconsisting of argon and helium.
 16. The method according to claim 9,further comprising aerosolizing the precursor feedstock prior tosupplying the precursor feedstock to the plasma applicator.